Fluid heat exchange apparatus



June 7, 1938. P. R. CASSIDY ET AL 2,120,125

FLUID HEAT EXCHANGE APPARATUS Original Filed Jan. 20, 1934 2Sheets-Sheet cooooooooooodoooooooooun :oooooooooooooooooo com 2dooooooooooooooooooooo00oz :oooooooooooooooooooooo ooo:ooooomznooooooooooooooooo :oooon nnnoooooooooooooooo Howard 1 Kerr'INVENTOR .Perry 1Q. Cassz Isaac Harte!" ATTORNEY :oooooncooooooooooooooooo ooooooooooooooooooooooooo 2 9 e ennooooooooooooooooooooooo l w e e U 9 a;oooooooooooooooooooooo r We 0 e6 e e M Z a '9 e 0 a 9 e 9m 9 9 e 0 m In eM a e 9 9 9 A e e e e 9 F3 9 a3 8 n 2 n A 0 A 0 A1 A 4 2 June 7, 1938. P. R. CASSIDY ET AL FLUID HEATEXCHANGE APPARATUS Original Filed Jan. 20, 1934 2 Sheets-She et 2INVENTOR Perry 2. Cassza'y Isaac H ter BY Howard Ker-r Patented June 7,1938 UNITED STATES PATENT OFFICE FLUID HEAT EXCHANGE APPARATUS NewJersey Application January 20, 1934, Serial No. 707,442 Renewed June 9,1936 20 Claims. (Cl. 257-220) This invention relates to fluid heatexchange apparatus and it is here described with reference to aneconomizer used in connection with a steam boiler to raise thetemperature of feed water by transferring heat thereto from furnacegases after they have passed over the steam generating surfaces of theboiler, and where desired to generate steam after the water has reachedits boiling point.

It is an object of the invention to provide an extended surfaceeconomizer in which the tubes do not divert the gas flow so that theextended surface elements are rendered ineffective on account of beingpositioned in a tube fiow shadow. A further object of the invention isto provide an economizer with studded water tubes of suchcharacteristics that effective water heating may be accomplished withoutpreventing the economizer tubes from contacting with the furnace gases.

Afurther object of the invention is to provide extended surfacestructure having effective heat transfer capacity at the tube junctionby welding and by cross-section of weld, of a construction that isinexpensive and that does not impose stresses on tubes or surface by theact of welding suificient to harm either member or the joint.

Other objects will appear as the accompanying description proceeds.

The invention will be described with reference to the accompanyingdrawings, in which:

Fig. 1 is a view in the nature of a diagram matic view showing theillustrative economizer in operative relation to a steam boiler. 35 Fig.2 is a view in the nature of a vertical section taken on the lineindicated as 2--2 in Fig. 1, and-looking in the direction of the arrowsthere shown and illustrating the ends of circular section studs.

Fig. 3 is a vertical section of an economizer taken on the line 33 ofFig. 2, and along a plane at right angles to the plane in which Fig. 2is taken.

Fig. 4 is a detail view showing the relationship of a few of theeconomizer tubes with the longitudinal and transverse spacing strutsbetween the tubes.

Fig. 5 is a detail view of an embodiment of the invention in which theeconomizer tubes are pro- 50 vided with studs of rectangular instead ofcir-' cular section.

Fig. 6 is a vertical sectional view taken on the line 6-6 of Fig. 5.

Fig. 7 is a detail view showing one of the economizer tube endY-connectors indicated in Fig. 2.

Fig. 8 is a detail view in the nature of a horizontal section taken onthe line 8-8 of Fig. '7.

Fig. 9 is an end elevation of the Y-connector shown in Figs. 7 and 8.

Fig. 10 is a vertical section showing a modified form of economizer inwhich the economizer tubes with their rows of integrally attached studsare staggered with respect to each other.

The economizer l0 indicated in Fig. 1 of the drawings is acountercurrent economizer in which the water enters a series of tubes l2at the base of an economizer casing l4. As the water proceeds 'in azig-zag manner upwardly through these tubes to the boiler drum l6, it isheated by furnace gases proceeding downwardly from the boiler outlet IEto the stack opening 20 at' the base of the economizer casing. Theboiler parts indicated in Fig. 1 include a furnace 22 which is situatedbelow a bank of horizontally inclined steam generating tubes 24. Thegenerating tubes are connected at. their lower ends to a headerconstruction 26 of known form, the header being connected with the waterspace of the drum l6 by downtake nipples 28 extending across the path ofgases as they proceed from the boiler to the top of the economizer flue.

An arrangement of economizer tubes is indicated in Figs. 3 and 4 of thedrawings. As shown here, the tubes are provided with metallic studs 30of circular section which are preferably electrically resistance weldedto the tubes while held in radial position. There are two rows of studson each of the opposite sides of the tubes, and the studs in successivevertical rows are staggered with respect to each other as clearlyindicated in Fig. 2 of the drawings. After the studs are welded to thetubes they are bent so that their outer ends extend horizontally, or ina direction normal to the gas flow axis of the economizer and across thespace between adjacent tubes. This arrangement of the studs is quiteclearly shown in Figs. 3 and 4 of the drawings.

The studs 30 projecting horizontally from adjacent tubes terminate atpositions about midway of the space between those tubes, and the tubesare held properly spaced horizontally by struts 32 extendingtransversely of the tubes and each having one end welded to the tubes asshown at 34 in Fig. 4. Adjacent tubes in the same horizontal row arethus held so spaced that the studs of those tubes cannot contact witheach other,,or overlap, and so are free to expand without stressing thetubes.

Adjacent economizer tubes in the same vertical or loop of return bendtube are held in their' operative positions. As indicated in Fig. 2 ofthe drawings there are six of these tube lengths connected by returnbends to form a single return bend coil. The end tubes 40 and 42 ofthese coils are connected to similar coils above andbelow them byremovable return bends 44 and 46. At the other wall of the economizerflue adjacent tube lengths of the returnbendcoils are joined byY-connectors 48 having stems 50 extending through openings in the wall52 of the economizer flue. Some of the return bend connectors areprovided with hand-hole openings which are closed by hand-hole fittings54. These are shown in detail in Figs. '7, 8 and 9 where it is indicatedthat, each fitting consists of a valve member 56 and a bridge piece 58against which the nut 60 may be turned to close the opening in theY-connector.

In Fig. 10 of the drawings the tubes 62 in alternate horizontal rows arestaggered with respect to the tubes 64 of adjacent rows. Thisarrangement also effects a staggering of the studs arranged betweensuccessive rows. At the economizer wall 66 there are filler members 68secured to the walland extending to positions adjacent the ends of thestuds secured to the tubes 64 in order to limit short circuiting ofgases.

In either one of the embodiments of the invention there is sub-divisionof the heating gases to such a high degree by the large number ofclosely spaced small diameter studs that a relatively small number ofthe studded tubes may have the heat transfer effectiveness of a muchlarger number of tubes used without the studs. Also, in the .form ofextended surface economizer here shown,

a considerable proportion of the bare tube surface is left freelyexposed to contact with the heating gases. The extended surface elementsand the economizer tubes are also so arranged that none of the extendedsurface elements are in the tube shadows, or the gas eddies that form onthe down stream sides of transversely swept tubes. Furthermore, anincrease in heat transfer rate attends the arrangement of the studsbetween the tubes at the point of maximum gas velocity. By reason ofthis location of the extended surfaces there is a further increase ofgas velocity at the previous point of maximum velocity, as well as theattendant increase in rate of heat exchange.

Figs. 5 and 6 indicate an embodiment of the invention in which metallicvanes or blades 10, constituting rectangular section studs, areelectrically resistance welded to the economizertubes 12. Theserectangular section studs may be welded to the tubes along oppositesides and they may be arranged in pairs directly opposite each other asshown. This form of invention reduces the total number of weldingoperations required to form a given percentage of extended surface. Inthis embodiment of the invention, successive tubes in a vertical row maybe spaced in the same manner as are the tubes of the Fig. 3modification. Narments wherein the vanes on successive tubes in thevertical rows are staggered with respect to each other. As here shownthe tube 12 lies above the tube 16 and the studs 18 of the latter arestaggered with respect to the vanes 10 of the upper tubes 12.

In some cases it is advantageous to place studs so as to point towardthe direction from which the gases are approaching, when the tubespacing vertically is great enough so that they are not in tube shadowsand they may be used to supplement side studs or to replace them.

Although the invention has been described with reference to theparticular embodiments of the invention shown in the drawings, it is tobe understood that it is not limited thereto, but that it is of a scopecommensurate with the scope of the sub-joined claims. 1

What is claimed is:

1. In an extended surface economizer, a heating gas flue, water tubes inthe flue, and transverse metal bars welded to opposite sides of thetubes, the tubes being arranged in rows extending transversely of theflue with the bars of the tubes of a row disposed between parallelplanes tra'nsa verse to the flue and bounding the tubes of the row, andthe bars on successive tubes along the path of gas flow being disposedin staggered relationship.

2. In an extended surface counterflow economizer, a heating gas flue,water tubes in the flue, and transverse metal bars end welded toopposite sides of the tubes, the tubes being arranged in rows extendingtransversely of the flue with the bars of the tubes of a row disposedbetween parallel planes transverse to the flue and bounding the tubes ofthe row, the bars having a maximum width which is less than the diameterof the tubes.

3. In an economizer, a flue for heating gases, water conducting tubesextending across the flue and having more than 50% of their bare tubesurface exposed directly to heating gases,'and spaced cylindricalmetallic studs outside of the tube shadows and welded to the tubes toproject therefrom into the heating gases and transversely of i tweenadjacent tubes in the same transverse row and between pairs of paralleltransverse planes bounding said rows of tubes.

4. Inan economizer, successive horizontal and upright rows of watertubes, and metallic vanes positioned outside of the tube shadows andwelded to the opposite sides of the tubes at spaced positions thereon,the vanes on successive tubes in upright rows ,being staggered withrespect to each other, said vanes being disposed substantially whollywithin the inter-tube spaces between adjacent tubes in each of thehorizontal rows and between parallel planes bounding the individualhorizontal rows.

5. In an economizer, successivehorizontal rows of water tubes, andmetallic vanes welded to the tubes at spaced positions thereon andpositioned outside of the tube shadows, the vanes on successive tubesbeing staggered with respect to each other, said vanes being disposedsubstantially wholly within the inter-tube spaces between adjacent tubesin' each of the horizontal rows and between parallel planes bounding theindividual horizontal rows.

6. In an economizer, a flue for heating gases, water tubes extendingacross the flue and arranged in upright as well as horizontalrows,.return bends and. Y-connectors joining successive tubes in theupright rows so as to form flat coils or slabs of return-bend tubes,removable return bends connecting the successive coils, rows ofstaggered metallic studs welded to opposite sides of the tubes so as toextend transversely of the flue, upright struts welded to the tubes andpositioned between successive tubes in an upright row, and horizontalstruts interposed relative to successive tubes in the horizontal rowsand welded thereto to maintain the studs of those tubes out of contact.

7. In an economizer, a flue for heating gases, water tubes extendingacross the flue and arranged in upright as well as horizontal rows, rowsof staggered metallic studs welded to opposite sides of the tubes so asto extend transversely of the flue, upright struts welded to the tubesand positioned between-successive tubes in an upright row, andhorizontal struts interposed relative to successive tubes in thehorizontal rows and welded thereto to maintain the studs of those tubesout of contact.

8. In an economizer, a flue for heating gases, water tubes extendingacross the flue and arranged in longitudinal as well as transverse rows,rows of staggered metallic studs welded to opposite sides of the tubesso as to extend transversely of the flue, and transverse strutsinterposed relative to successive tubes in the transverse rows andwelded thereto to maintain the studs of those tubes out of contact.

9. A stud tube economizer comprising, a flue, a plurality of water tubesdisposed in a plurality of rows extending transversely of the flue withthe flue gases moving transversely of the tubes, and headed studsdisposed between the tubes of the rows and outside of the tube shadowsthereby leaving the inter-row spaces free, the studs being welded to thetubes at their headed ends and extending transversely of the flue aswell as the tubes.

10. A stud tube economizer comprising, a flue, water tubes in spacedrows arranged both transversely and longitudinally of the flue, andheaded studs welded to the tubes along their sides bounding the spacesbetween the longitudinal rows and positioned outside of the tube shadowsand the spaces between the transverse rows.

1 11. An extended surface economizer comprising, in combination, a fluefor heating gases, water conducting tubes in the flue, and staggeredmetallic studs welded to the tubes and entirely positioned in the mostactive gas flow zones.

12. In an extended surface economizer, a gas flue, water tubes in spacedrows arranged transversely of the flue, and metallic studs welded to thetubes so as to extend only across the gas flow space between adjacenttubes in contact with furnace gases, the spaces between the transverserows of tubes being free.

13. In an extended surface economizer, a heating gas flue, successiverows of tubes arranged transversely and longitudinally of the flue withgas flow lanes between them, and transverse metal studs welded toopposite sides of the tubes with the studs of the tubes of a rowdisposed between parallel planes extending transversely of the flue andbounding the tubes of the row, all of the active surface extensionsformed by the studs projecting from the tubes toward each other acrossthe gas flow lanes.

14. In an extended surface economizer, a flue for heating gases, waterconducting tubes spaced in rows arranged transversely and longitudinallyof the flue, and metallic vanes or blades constituting extended surfacemetalelements welded to opposite sides of the tubes so as to extendtransversely of the longitudinal axes of the tubes in contact withfurnace gases, the vanes on successive tubes being staggered and all ofthe economlzer heating surfaces provided by the tubes and vanes beingdisposed in a succession of spaced transverse zones with free spacesbetween the zones.

15. In fluid heat exchange apparatus, means forming a pass for the flowof a heat exchange fluid, a bank of tubes extending across the pass andarranged in rows arranged transversely of the flow of said heat exchangefluid, extended surface metallic studs welded to the tubes andpositioned wholly within the zones of maximum velocity of the heatexchange fluid so as to leave the spaces between said transverse tuberows free of obstruction by the tubes or the studs and to cause maximumheat exchange with a minimum of extended surface, and means extendingacross said spaces between the transverse tube rows and engaging thetubes to maintain them in their transverse row relationships.

16. In fluid heat exchange apparatus, means forming a pass for the flowof a heat exchange fluid, a bank of tubes extending across the pass andarranged in rows arranged transversely of the flow of said heat exchangefluid, and extended surface metallic studs welded to the tubes andpositioned wholly within the zones of maximum velocity of the heatexchange fluid so as to leave the spaces between said transverse tuberows free of obstruction by the tubes or the studs and to cause maximumheat exchange with a minimum of extended surface.

1'7. In fluid heat exchange apparatus, means forming a pass for the flowof a heat exchange fluid, a bank of tubes extending across the pass andarranged in rows disposed transversely of the flow of said heat exchangefluid, extended surface metallic studs welded to the tubes andpositioned wholly within the zones of maximum velocity of the heatexchange fluid so as to leave the spaces between said transverse tuberows free of obstruction by the tubes or the studs and to cause maximumheat exchange with a minimum of extended surface, and means extendingacross said spaces between the transverse tube rows and engaging thetubes to maintain them in their transverse row relationships, the studsextending toward each other from adjacent tubes in the same transverserow having full width ends facing each other so as to limit the extentto which the tubes may move transversely from their original positions.

18. In an extended surface economizer, means forming a gas pass, tubesof cylindrical cross-section arranged within said gas pass fortransverse flow of the gas with respect thereto, and separate extendedsurface elements projecting from each tube across the path of gas flowand disposed on both sides of the axial center line on each tube, saidextended surface elements being spaced in the direction of gas flow oneach tube.

19. In an extended surface economizer, means forming a gas pass, spacedtubes of cylindrical cross-section within said gas pass and arranged fortransverse flow of the gas with respect thereto, and separate extendedsurface elements welded to each tube so as to extend across the path ofgas flow and disposed on both sides of the axial center line of eachtube, said extended surface prising, in combination, a bank of spacedtubes extending transversely of the flow of furnace gases passing fromsaid steam generating section, and small rod-like metallic studssupported by and in good heat transfer relation with said tubes,

said studs extending transversely of the direction of gas flow withfacing surfaces of successive tubes in that direction bare of studs,successive tubes transversely of the gas flow having their.

studs spaced and extending normally to the direction of gas flow andterminating at positions substantially midway between said tubes.

PERRY R. cAssiDY. ISAAC HARTER. HOWARD J. KERR.

